Thermo-treatment affects Quercus cerris L. wood properties and the antioxidant activity and chemical composition of its by-product extracts

Nowadays, there is an increasing interest on thermo-treatment and its effects on wood structure and extraction processes, connected to the wood use for industrial application and for its use as biorefinery. The present investigation aimed to provide the main changes on wood properties (mass loss, color variation and modulus of elasticity) and a comparative analysis of the antioxidant properties and GC–MS profile of the extracts from Turkey oak (Quercus cerris L.) wood. Untreated and thermo-treated wood (170 °C x 3 h) samples were compared. Thermo-treatment induced a mass loss (5.1%) in wood, a darkening of color surface (ΔE = 7.6) and a decrease of MOE (4.1%). Moreover samples were extracted using different techniques: maceration (ME), ultrasound assisted extraction (UAE) and accelerated solvent extraction (ASE). Extracts were tested to evaluate the content of polyphenols and flavonoids along with the in vitro antioxidant activity. Results showed that extracts obtained from thermo-treated wood reported the highest Relative Antioxidant Capacity Index and extraction techniques affected the value in the following rating: UAE > ME > ASE. Qualitative and quantitative measurements of chemical compounds were carried out by GC–MS system. Taking into account the thermo-treatment and extraction techniques, principal component analysis (PCA) was performed also in order to evaluate the relationships among principal chemical compounds. According to results obtained, thermo-treatment and extraction technique had a determinant role in the antioxidant efficiency and, consequently, on the potential application of extracts

Feeding emitters for microirrigation with a digestate liquid fraction up to 25% dilution did not reduce their performance

Irrigation with wastewater can strongly contribute to the reduction of water abstraction in agriculture with an especial interest in arid and semiarid areas. However, its use can have drawbacks to both soil and micro-irrigation systems, especially when the total solids in the wastewater are high, such as in digestate liquid fractions (DLF) from plant material. The aim of this study was thus to evaluate the performances of a serpentine shaped micro-emitter injected with a hydrocyclone filtered DLF (HF-DLF) from corn + barley biomass and evaluate the traits of the liquid released within a 8-h irrigation cycle. HF-DLF was injected at 10%, 25%, and 50% dilution compared to tap water (at pH = 7.84) and the system performances were measured. No clogging was found, which likely depended on both the shape of the emitter and the high-pressure head (200 kPa). HF-DLF dilution at 10%, 25%, and 50% consisted in +1.9%, +3.5, and -4.9% amount of liquid released compared to the control. Fluid temperature during irrigation (from 9:00 to 17:00) did not explain the difference in the released amounts of liquid. In 10% HF-DLF % and 25% HF-DLF, a pH difference of + 0.321 ± 0.014 pH units compared to the control was found, and such difference was constant for both dilutions and at increasing the time. In contrast, 50% HF-DLF increased pH by around a half point and such difference increased with time. Similar differences among treatments were found for the total solids in the liquid. These results indicate that 50% HF-DLF was accumulating materials in the serpentine. These results suggest that a low diluted HF-DLF could directly be injected in irrigation systems with few drawbacks for the irrigation system and contribute to water conservation since such wastewater are available from the late spring to the early fall, when water requirements are high

From biomass of poplar utilizations to byproducts

According to recent bioeconomy programs, chemical compounds derived from natural sources will be more available in regions where these compounds can be obtained economically than more expensive synthetic chemicals. In addition, the biorefinery is becoming an important aspect for green chemistry development aimed at ensuring the necessity to achieve the best objectives as favourable as possible from restricted natural resources such as forest biomass. One of the main scope is to generate diversified, innovative and renewable products using on-site bioresources such as biomass of wood and tree residues. Poplar tree species, including all their huge varieties, are largely cultivated in the world as a fast growing bioenergy crop. However the enormous potential of this specie in the other fields is still under-evaluated. The aim of this study was to verify the influence of thermal treatment at 180, 200 and 220 °C on wood extracts obtained via three different extraction techniques: Maceration, ultrasound-assisted extraction and accelerated solvent extraction. Results showed the effect of heat treatments and extraction techniques on polyphenol, flavonoid contents and antioxidant activity. This investigation clearly showed the differential effects of temperature and extraction techniques on both antioxidant activity and secondary compounds contents

New Insight and Evaluation of the Extractives from Thermo-Treated Woods

Several studies reported changes in physical and mechanical wood characteristics due to thermotreatment but the information on the considerable significance and industrial potential of the role of extractives are underevaluted. The heat treatment modifies the chemical composition of the wood organic compounds and consequently its secondary metabolites content. The differences of the chemical composition and the antioxidant activity of the native extracts of a species and the extracts obtained from thermo-treated wood is poorly investigated. In this preliminary study the extraction of secondary metabolites from thermo-treated (at temperature between 170-220 °C for 3 hours) and untreated wood of several species was carried out and the content of polyphenols, tannins and flavonoids and the antioxidant activity of the extractives were also evaluated. The heat treatment clearly increased the extract yield in some investigated wood species, whereas in others the extractive yields were almost unchanged. The content of polyphenols, tannins and flavonoids was also higher in some species after the thermal treatment compared with other species. All samples, heat treated and untreated, exhibited antioxidant activity by DPPH assay. This activity increases with the content of secondary metabolites of the extracts, but not always the highest activity was exhibited by the heat treated extract. These differences were originated from intrinsic properties of lignin and other wood components and they are specific for each species. Further investigations will be focused on the identification of the compounds in untreated and heat treated samples and to deepen the biological activity of the extracts

How change some properties of poplar wood surface with extractives of durable wood species.

All woods contain extractives and they may include hydrolyzable or condensed tannins, flavonoids, lignins, stilbenes, faty acids, resin acids, other complex terpenoids, waxes, sterols, sugars, cyclitols and starch. The extractives ofen are the main responsible of many characteristics and possible uses of wood, such as colour, flammability, hygroscopicity and permeability. The wetability of wood is an important parameter that provides a series of information on the interaction between the wood surface and liquids, such as water or adhesives. In this work the contact angle of a sessile drop and the colour stability of the poplar (Populus spp.) wood surface afer immersion and afer accelerated weathering test into five types of extractives obtained from durable wood Castanea sativa Mill., Cedrus deodara Roxb., Qercus fraineto Ten., Qercus petraea Liebl. and Larix decidua Mill. were investigated. Extraction was carried out with a mixture of water and ethanol (30:70 v/v) by extraction system ASE 100 at 110° with a pressure of 100 bars. For each extractives solution three replicas have been done and five drops have been recorded. Distilled water for the contact angle afer immersion and afer accelerated weathe - ring test was used for a time of 120 sec. The color change of the specimens were also measured in form of CIE L*a*b* before and afer accelerated ageing to determine changes in lightness (ΔL), colorimetric parameters Δa, Δb, and overall color (ΔE). The results revealed that poplar wood surface were diferentially afected by the spe - cies afer immersion. Afer accelerated weathering test the efect of extractives on wetability disappeared. In terms of the colour diference (ΔE), afer immersion the smallest value has been observed when extractives of cedar and larch were used. However, the same extractives afer accelerated ageing, showed a higher value of ΔE compared to the other extractives. In fact, afer ageing, the extractives of chestnut and both oak, conferred a more stable color of poplar wood surface. In conclusion this study showed that some types of extractives could be used as a natural compound to change the absorption of the water and the colour stability